Category Archives: Windows 8.1

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A remarkably little known feature in Windows Sever 2012 R2 (and Windows 8.1) is the ability to export one or multiple running virtual machines.

You just select right click in the Hyper-V manager and select Export from the context menu and follow the wizard to select an export location. Easy. This is also possible via PowerShell so you can automate this. The result is a VM you can import which gives you a copy of the original virtual machine in a saved state, at the point in time that you exported it.

More people seem to know about the capability to export a checkpoint of a running virtual machine, not so many of the capability to export a running VM itself. I noticed this because some people figured the latter was a new feature in Windows 2016. No it’s not. We’ve had this option since Windows 8.1 and Windows Server 2012 R2.

So why even have the option of exporting a checkpoint of a running VM? Because this enables you to have exports from various points in time, which is pretty cool and handy during test and development and trouble shooting or lab work. As a standard checkpoint has state in Windows Server 2012 R2 I prefer to shut down the VM, create a checkpoint and start the VM again. When I then export that checkpoint I don’t have to worry about the state in the VM at that point in time as it was shut down.

For some workloads this isn’t a big deal bit for some this is not a great experience, hence the fact that checkpoints are “”not supported in production but for test and dev.

In Windows Server 2016 we now have production checkpoints. That means that when we apply such checkpoints we have a consistent state just like when we restore VM from a backup. You’ll have to boot it up after applying the checkpoint, they do not appear running with the state at the time the snapshot was taken. Well, not unless you opt to create standard checkpoints. The reduces the need for me to shut down a VM before I create a checkpoint to export in many cases.

When you export a running VM in Windows Server 2016 you’ll have a copy of it in saved state. Just like you did in Windows Server 2012 R2, no change there. When you import that you’ll have a VM in saved state that you need to start up. If you want an application consistent copy, create a production checkpoint first and export that one.

So there you go. The feature to live export a running virtual machine was here before and it’s still here. The real extra capability with live exports comes from leveraging the live export of a checkpoint of a running virtual machine and the fact that we now have production checkpoints.

When you’re discovering how to get discrete device assignment to work you have some potential bumps that might trip you up. So what are the issues to watch out for when configuring Discrete Device Assignment? We’ll share some here but note this is from testing with Windows Server 2016 Technical Preview 4. Changes can and probably will happen before RTM.

Check the configuration version of the VM

When you try to add a GPU to a VM via Discrete Device Assignment you’ll get an error when the VM has version 5.0 in stead of 7.x. This can easily happen when you move VMs from older versions to a shiny new Windows 2016 environment as in the example below:

Naturally all of this is logged in the Hyper-V-VMMS Admin logs as well

Mind your Dynamic Memory settings

Another thing you need to watch out for is that when you use dynamic memory the startup memory and the minimum memory values have to match. So minimum memory cannot be lower than the startup memory. Do not that this is TPv4 and things might change.

Cannot add the device to ‘W2K12R2’ as that virtual machine has Dynamic Memory configured with different startup memory and minimum memory values. When adding a device, the virtual machine must be configured with equal startup memory and minimum memory values.(Virtual machine ID 592A920F-B0E9-480C-9052-A397B377BCC9)

If you try to change this on a VM with discrete device assignment enabled you’ll also find that this isn’t allowed.

Cannot perform the operation for ‘W2K12R2’ as the specified memory settings are not compatible for device assignment. The startup memory size and minimum memory size must be equal when Dynamic Memory is enabled and devices are also assigned.(Virtual machine ID 592A920F-B0E9-480C-9052-A397B377BCC9)

Set the automatic stop action to “Turn off the virtual machine”

I already mentioned this in the blog but you need to make sure that the automatic stop action for the virtual machine is set to “turn off the virtual machine and not to the default of “save the virtual machine state”. You cannot use DDA unless you do so.

Cannot add the device to ‘W2K12R2’ as that virtual machine is configured to go to saved state on host shutdown. (Virtual machine ID 592A920F-B0E9-480C-9052-A397B377BCC9)

Again, changing this on a VM that has DDA assigned will not work.

Discrete means one on one

Remember that you cannot assign a device to more than one VM. The thing here is it won’t block you when both VMs are shut down, at least not in TPv4. But It’s dedicated and won’t work. When you do and you try to start any of those VMs it won’t work.

An error occurred while attempting to start the selected virtual machine(s).

‘RFX-WIN10ENT’ failed to start.

Virtual Pci Express Port (Instance ID 9B15DD32-5F94-46EF-8524-501007830322): Failed to Power on with Error ‘The device is in use by an active process and cannot be disconnected.’.

When you try to assign a GPU to a VM that is assigned to a running VM it will block you!

The dive Cleary identifies the VM the device is already assigned to.

Add-VMAssignableDevice -LocationPath $LocationPathOfDismountedDA -VMName RFX-WIN10ENTAdd-VMAssignableDevice : ‘RFX-WIN10ENT’ failed to add resources to ‘RFX-WIN10ENT’.
Virtual Pci Express Port (Instance ID EA7CB907-C38A-4396-97E0-A9A8F3C2D1B0): Failed to Power on with Error ‘The device
is in use by an active process and cannot be disconnected.’.
‘RFX-WIN10ENT’ failed to add resources. (Virtual machine ID 425A366E-E380-4D8C-AADE-DE16EAC0A104)
‘RFX-WIN10ENT’ Virtual Pci Express Port (Instance ID EA7CB907-C38A-4396-97E0-A9A8F3C2D1B0): Failed to Power on with
Error ‘The device is in use by an active process and cannot be disconnected.’ (0x80070964). (Virtual machine ID
425A366E-E380-4D8C-AADE-DE16EAC0A104)
Could not allocate the PCI Express device with the Plug and Play Device Instance path
‘PCIP\VEN_10DE&DEV_0FF2&SUBSYS_101210DE&REV_A1\6&17F903&0&00400010’ because it is already in use by another VM.
At line:1 char:1
+ Add-VMAssignableDevice -LocationPath $LocationPathOfDismountedDA -VMN …
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [Add-VMAssignableDevice], VirtualizationException
+ FullyQualifiedErrorId : OperationFailed,Microsoft.HyperV.PowerShell.Commands.AddVmAssignableDevice

Shut down your VM to make change to DDA

Last but not least to use DDA (assign, configure) with a VM you have to shut it down. Removing devices whilst the VM is running isn’t blocked. But, he results can be quite “harsh”. This is me removing a DDA GPU form a Windows 2012 R2 VM whilst it’s running.

The fun part is that you can add it again while the VM is running and with will work, but it’s not a healthy thing to do.

As stated above, these notes are from testing with Windows Server 2016 Technical Preview 4 so thing can still change. Happy testing!

Why this little shout out? Well it’s a remote code execution vulnerability that can leverage the guest to run code on the host.

This security update resolves vulnerabilities in Microsoft Windows. The most severe of the vulnerabilities could allow remote code execution if an authenticated attacker on a guest operating system runs a specially crafted application that causes the Hyper-V host operating system to execute arbitrary code. Customers who have not enabled the Hyper-V role are not affected.

Select the version you need for the KMS server or servers you use and install them.

Launch the update by launching Windows8.1-KB3058168-x64.msu

Click “Yes” to install the update

Install the update

Restart the KMS Server

So there you go, you’re ready to to start deploying Windows 10 Enterprise edition which can then be activated by your KMS server when the new client OS is generally available. Good luck.

Closing note: Don’t even bother posting comments where you ask for KMS Server keys or MAK keys for Windows 10. As I’ve stated before, while it might be more fun to join the pirates we’re the navy and as such we don’t condone piracy . Got it? GOOD!